Question about serial cable for ln40b630n1f
Posted: Fri Dec 05, 2014 6:31 pm
Hello. I have a dead ln40b630 that I got for almost nothing. It looks like the main board switches itself on/off--maybe due to firmware corruption. I would like to try to get access to the uboot to reflash it if possible. I removed the ps_on pin from the power connector so the main board stays powered up.
I made an exlink cable as shown in the wiki for the b-series. I dusted off an old pc and connected the cable to a real serial port. When I switch the tv on, I see voltages of -3 to +5 on the rx line, but I can't get anything to appear in putty (serial console). Loopback works fine, so I know the computer's port is working. Not sure if these voltages are conventional rs232 or ttl serial, but my understanding is that ttl serial doesn't swing negative.
Here's what I have tried:
1. swapping rx/tx--that didn't help
2. changing baud rates--that didn't help (seems like 9600-8-n-1 should be ok from the wiki)
3. tried a ftdi-based usb serial cable--that didn't work either though I did see a period on the console every second or so (".......")
4. looked for a debug switch or pads on the main board--can't find anything
Any thoughts on this? Main board could just be bad and serial not working but it seems strange that I get some kind of voltage changes on the exlink port.
I made an exlink cable as shown in the wiki for the b-series. I dusted off an old pc and connected the cable to a real serial port. When I switch the tv on, I see voltages of -3 to +5 on the rx line, but I can't get anything to appear in putty (serial console). Loopback works fine, so I know the computer's port is working. Not sure if these voltages are conventional rs232 or ttl serial, but my understanding is that ttl serial doesn't swing negative.
Here's what I have tried:
1. swapping rx/tx--that didn't help
2. changing baud rates--that didn't help (seems like 9600-8-n-1 should be ok from the wiki)
3. tried a ftdi-based usb serial cable--that didn't work either though I did see a period on the console every second or so (".......")
4. looked for a debug switch or pads on the main board--can't find anything
Any thoughts on this? Main board could just be bad and serial not working but it seems strange that I get some kind of voltage changes on the exlink port.